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Educational aspects of medieval Serbian wall painting
Get PDFObrazovni aspekti srednjovekovnog srpskog zidnog slikarstva prisutni su u školskoj nastavi, kao i u nastavnim planovima i programima za sve cikluse u obrazovnom sistemu Republike Srbije. Učenici imaju priliku da se upoznaju sa osnovama živopisa od osnovne škole kroz nastavne jedinice iz Likovne kulture, Istorije, Srpskog jezika i književnosti, Crtanja, slikanja i vajanja i Verske nastave. Primećeni istorijski diskontinuitet u teorijskom izučavanju i razumevanju vizantijskog i srpskog zidnog slikarstva jedan je od razloga da se istraživanje usmeri ka obrazovnim aspektima ovog vida slikarstva. Cilj rada je da se sagleda aktuelno stanje što bi predstavljalo polaznu tačku za formiranje preporuka za njegovo unapređenje.Educational aspects of medieval Serbian wall painting are present in school teaching, as well as in curricula for all cycles in the education system of the Republic of Serbia. Students have the opportunity to learn about the basics of fresco painting from elementary school through the teaching units of Art, History, Serbian language and literature, Drawing, painting and sculpting, and Religious teaching. The observed historical discontinuity in the theoretical study and understanding of Byzantine and Serbian wall painting is one of the reasons to deal with their educational aspects in this paper. The goal of the paper is to review the current situation, which would be the starting point for the formation of recommendations for its improvement
Understanding the Effect of Synthesis and Sintering Temperature on the Functional Properties of Barium Titanate/ Cobalt Ferrite Composites
No full textTo investigate the effect of synthesis procedure and sintering temperature on the functional properties of perovskite/spinel ceramics, BaTiO3/CoFe2O4 composites were prepared by thermal decomposition, coprecipitation, and microemulsion method, and sintered at 1150°C and 1300°C. The phase composition and morphology of as-prepared powders as well as sintered ceramics were thoroughly examined by X-ray powder diffraction (XRPD) and scanning electron microscopy (SEM) coupled with electron dispersive spectroscopy (EDS). The dielectric and ferroelectric measurements were performed in detail. Generally, the samples sintered at 1300°C had better performances than those sintered at 1150°C. The composite synthesized by thermal decomposition and sintered at 1300 °C stands out among other prepared BaTiO3/CoFe2O4 ceramics, owing to high stability in the wide frequency range and low leakage currents. The obtained results indicate that such composite might be successfully applied as a functional multiferroic
Micronutrients
No full textThe functions of iron, manganese, copper, zinc, nickel, molybdenum, boron, and chlorine in plants are discussed. Iron
(Fe) plays a crucial role in redox systems in cells and in various enzymes. The strategies of dicotyledonous and graminaceous
plants to acquire Fe are described. Manganese (Mn) and copper (Cu) are important for redox systems and as
activators of various enzymes involved in photosynthesis, detoxification of superoxide radicals, and the synthesis of lignin.
Zinc (Zn) plays a key role in the structural and functional integrity of cell membranes, biosynthesis of proteins and
detoxification of superoxide radicals. Nickel (Ni) is involved in nitrogen (N) metabolism as metal component of the
enzyme urease. Molybdenum (Mo) is important for N metabolism as metal component of nitrogenase (N2 fixation) and
nitrate reductase. Boron (B) is crucial for the stability and function of cell wall and membranes, whereas chlorine (Cl)
is essential for the proper functioning of photosystem II (PS II) and cell osmotic regulation. For each micronutrient, the
effects of deficiency and toxicity are described
ACCLIMATION OF PEDUNCULATE OAK SEEDLINGS TO DIFFERENT LIGHT CONDITIONS IN THE FIRST MONTHS AFTER GERMINATION
Get PDFThe first months are the most sensitive phase of oak seedling development. Light conditions have an important role in this sense, both from the physiological and management viewpoint. We investigated the response of pedunculate oak seedlings to three growth light intensities (100, 550 and 2000 μmol cm−2s−1) during development of the first and second growth flush. The low and high light intensities of PAR are supposed to mimic the effects of solar radiation under extreme natural conditions (closed canopy and open field). The response of seedlings to different light intensities was evaluated by determining the photochemical activity of photosystem II, leaf chlorophyll concentration and epidermal flavonoid accumulation for both growth flushes. At the end of the experiment (after 4.5 months) the effects of different treatments on growth parameters were also determined. We showed here that oak seedlings responded to varying light intensities by modifying their physiological and morphological traits of successive growth flushes. At medium light, seedlings had the highest PSII photochemical activity in the 2nd flush. High light induced very low photochemical efficiency of photosystem II in both growth flushes indicating the development of high non-photochemical quenching of chlorophyll fluorescence as part of photoprotective mechanism. In accordance with high photosynthetic yield at ML, the investment of photosynthates in growth, especially biomass allocation towards root system was confirmed. ML was optimal for seedling development in the first months. The results may contribute to a better understanding of oak seedling development and acclimation and could have importance for oak natural regeneration
Examination of the doping effects of samarium (Sm3+) and zirconium (Zr4+) on the photocatalytic activity of TiO2 nanofibers
No full textPure and samarium (Sm3+) - or zirconium (Zr4+)-doped TiO2 nanofibers were synthesized by electro-
spinning method followed by calcination at 500 °C for 1 h. As-spun fibers were smooth, straight and
continuous, whilst EDS analysis confirmed the fiber composition and incorporation of dopants in
the fibers. Doping with Sm3+ and Zr4+ greatly inhibited the phase transformation of anatase to
rutile, by surrounding of Sm3+ ions through formation of Ti-O-Sm bonds and by replacement of
Ti4+ ions with larger Zr4+ ions. This was confirmed by HRTEM and SAED analysis. The size of
nanofibers was determined to be 133 nm, 175 nm and 155 nm for pure, (0.5%)Sm3+:TiO2 and
(1%)Zr4+:TiO2, respectively. After cal- cination, TiO2 crystal lattice with interplanar spacing of
0.353 nm of (101) crystal plane was not significantly disturbed by Sm doping whilst crystal
lattice spacing of 0.357 nm of (101) planes of anatase phase in case TiO2:1.0%Zr4+,
significantly differs from the value of pure TiO2 (0.352 nm), thus implying that Zr was
doped into substitutional sites of the TiO2 lattice. The indirect band gaps were
calculated to be in the range 3.07–3.24 eV. TiO2:0.5%Sm3+ and TiO2:1.0%Zr4+ exhibited higher
specific surface area, of 47.1 and 59.4 m2/g, respectively, than pure TiO2 fibers (19.7 m2/g).
Effects of Sm3+ and Zr4+ dopant content on the photodegradation efficiency of methylene blue (MB)
were studied. TiO2:0.5%Sm3+ and TiO2:1.0%Zr4+ nanofibers have shown the highest photocatalytic
activity of 97% and 98% with constant rates 0.01768 min−1 and 0.01939 min−1,
respectively, within180 min irradiation under
visible light.This is the peered review of the paper: Ahmetović, S., Vasiljevic, Z. Z., Rajić, V., Bartolić, D., Novaković, M., Tadić, N. B., Cvjetićanin, N.,& Nikolic, M.. (2023). Examination of the doping effects of samarium (Sm3+) and zirconium (Zr4+) on the photocatalytic activity of TiO2 nanofibers. in Journal of Alloys and Compounds
Elsevier., 930, 167423.
[https://doi.org/10.1016/j.jallcom.2022.167423
Astroglial Cell-to-Cell Interaction with Autoreactive Immune Cells in Experimental Autoimmune Encephalomyelitis Involves P2X7 Receptor, 3-Integrin, and Connexin-43
Get PDFIn multiple sclerosis (MS), glial cells astrocytes interact with the autoreactive immune cells that attack the central nervous system (CNS), which causes and sustains neuroinflammation. However, little is known about the direct interaction between these cells when they are in close proximity in the inflamed CNS. By using an experimental autoimmune encephalomyelitis (EAE) model of MS, we previously found that in the proximity of autoreactive CNS-infiltrated immune cells (CNS-IICs), astrocytes respond with a rapid calcium increase that is mediated by the autocrine P2X7 receptor (P2X7R) activation. We now reveal that the mechanisms regulating this direct interaction of astrocytes and CNS-IICs involve the coupling between P2X7R, connexin-43, and β3-integrin. We found that P2X7R and astroglial connexin-43 interact and concentrate in the immediate proximity of the CNS-IICs in EAE. P2X7R also interacts with β3-integrin, and the block of astroglial αvβ3-integrin reduces the P2X7R-dependent calcium response of astrocytes upon encountering CNS-IICs. This interaction was dependent on astroglial mitochondrial activity, which regulated the ATP-driven P2X7R activation and facilitated the termination of the astrocytic calcium response evoked by CNS-IICs. By further defining the interactions between the CNS and the immune system, our findings provide a novel perspective toward expanding integrin-targeting therapeutic approaches for MS treatment by controlling the cell–cell interactions between astrocytes and CNS-IICs.casopis je u kategoriji M2
In situ detection of the genotoxic potential as one of the lines of evidence in the weight-of-evidence approach—the Joint Danube Survey 4 Case Study
No full textEnvironmental studies which aim to assess the ecological impact of chemical and other types of pollution should employ a complex weight-of-evidence approach with multiple lines of evidence (LoEs). This study focused on in situ genotoxicological methods such as the comet and micronucleus assays and randomly amplified polymorphic DNA analysis as one of the multiple LoEs (LoE3) on the fish species Alburnus alburnus (bleak) as a bioindicator. The study was carried out within the Joint Danube Survey 4 (JDS4) at nine sites in the Danube River Basin in the Republic of Serbia. Out of nine sampling sites, two were situated at the Tisa, Sava, and Velika Morava rivers, and three sites were at the Danube River. The three additionally employed LoEs were: SumTUwater calculated based on the monitoring data in the database of the Serbian Environmental Protection Agency (SEPA) (LoE1); in vitro analyses of JDS4 water extracts employing genotoxicological methods (LoE2); assessment of the ecological status/potential by SEPA and indication of the ecological status for the sites performed within the JDS4 (LoE4). The analyzed biomarker responses in the bleak were integrated into the unique integrated biomarker response index which was used to rank the sites. The highest pollution pressure was recorded at JDS4 39 and JDS4 36, while the lowest was at JDS4 35. The impact of pollution was confirmed at three sites, JDS4 33, 40, and 41, by all four LoEs. At other sampling sites, a difference was observed regarding the pollution depending on the employed LoEs. This indicates the importance of implementing a comprehensive weight-of-evidence approach to ensure the impact of pollution is not overlooked when using only one LoE as is often the case in environmental studies
Biosynthesis of ZnO nanoparticles using agro-waste with antibacterial and antioxidant activity
Get PDFGreen synthesis is a more sustainable option using renewable biomass such as plants as
reducing or stabilizing agents compared to toxic chemical compounds. These biological
substances also behave as capping agents, which control the size and shape of the
nanoparticles. In this work, ZnO nanoparticles (NPs) have been prepared via a simple, low
cost and ecofriendly method using citrus fruit peel and extracts as biological reducing agents.
Zinc nitrate and zinc acetate were used as a source of zinc ions.XRD analysis revealed the
formation of a ZnO wurtzite phase without impurities. Synthesized ZnO NPs with an average
electronic band gap ∼3 eV were obtained and found to have round-like, hexagonal-like or
needle-like structures depending on precursor type. EDS analysis showed a homogeoneous
distribution in Zn and O elements, attributed to single-phase ZnO constituents. Antibacterial
and antioxidant activities of synthesized NPs were evaluated. Obtained results showed that
ZnO synthesized from nitrate precursors are more effective in inhibiting growth of
Salmonella and Staphylococcus Aureus. Antioxidant activity of ZnO NPs determined using
CUPRAC and ABTS assays showed higher activity of ZnO obtained using nitrate precursors.
The maximum scavenging activity of 90% was observed at the concentration of 10 mg/m
Photocatalytic degradation of Reactive Orange 16 dye using TiO2/PPy nanocomposites under simulated solar light
Get PDFIt is well known that titanium dioxide is usually used as a photocatalyst due to its
nontoxicity, low cost, and stability. Conductive polymer, polypyrrole (PPy) is also
appropriate for photocatalytic application being stable and easy to synthesize. The aim of
this study was to obtain TiO2/PPy composites reaching higher photocatalytic efficiency
compared to pure TiO2. Therefore, TiO2 was synthesized by the hydrothermal route,
while PPy was obtained by the chemical oxidative polymerization method. TiO2/x% PPy
nanocomposites (x = 0, 0.5, 1, 1.5, 3, 5 wt.%) were prepared by hand-mixing of powders
in agate mortar for 30 min in order to find the optimal PPy content. Obtained materials
were characterized by XRD, FTIR, TG/DSC, FESEM, and UV-Vis methods while their
photocatalytic activity was estimated towards degradation of Reactive Orange 16 dye
(RO16). A kinetic study was performed and a detailed mechanism of RO16
photocatalytic degradation in the presence of TiO2/PPy composites was proposed based
on scavenger tests. The results showed that, despite PPy addition, TiO2 was present in
anatase form in all samples with sufficiently small crystallites (around 26 nm) and
preserved structure with no significant deviations in unit cell parameters. The band gap
energy decreased with increasing of PPy content, from 3.14 eV for pure TiO2 to 2.94 eV
for TiO2/5% PPy. All the obtained nanocomposites demonstrated higher photocatalytic
activity than pure TiO2, whereby TiO2/1% PPy nanocomposite was the most efficient by
degrading 99.6% of the dye for 105 min under simulated solar light. Therefore, the
amount of 1 wt.% should be consider as optimal amount of PPy in a composite. It is
established that the photodegradation of RO16 using TiO2/PPy nanocomposites follows
pseudo-first kinetic order. RO16 photocatalytic degradation mechanism in the presence
of TiO2/PPy nanocomposites can be well described by direct Z-scheme heterojunction
which has never been reported for TiO2/PPy system
INVESTIGATING THE EFFECTS OF Zr DOPING ON THE TITANIUM DIOXIDE NANOFIBRES
Get PDFIn this work, titanium dioxide (TiO2) nanofibers doped with 0.5–5 mol%
zirconium ions (Zr4+) were synthesized by combining the sol-gel process and
electrospinning method, and calcined at 500 °C. The morphological, structural and
optical properties of pure and Zr-doped TiO2 nanofibers were investigated. According to
the XRD and FTIR analyses, the addition of Zr as a dopant suppressed the
transformation of anatase to rutile phase. Scanning electron microscopy showed that all
fibers were smooth, fragile and randomly oriented after the calcination process. HRTEM
analysis revealed that Zr4+ ions were incorporated at the substitutional sites in the anatase
TiO2 crystalline lattice. The photocatalytic efficiency for degradation of methylene blue
(MB) was examined for both pure and Zr-doped TiO2 samples. Nanofibers doped with
1% of Zr4+ ions have shown the highest photocatalytic activity of 98%, wich can be
explained by considering lower PL intensity in the PL spectrum of this sample,
indicating suppressed electron-hole recombination